1. Field of the Invention
The invention relates to a method and an apparatus for separating the scrap cuttings from a panel that was punched or cut from a sheet of material and an arrangement for producing a panel from a sheet of material.
2. Description of the Background Art
Methods known in the art for producing blanks for collapsible folding boxes from cardboard sheets are flatbed-punching methods; they provide that the sheet of cardboard is placed inside a punching tool of a punching machine and onto a platen. Subsequently, a punching template, which is equipped with punching and scoring dies on its underside, is brought downward with great force and punches out panels (usable components).
For the subsequent separation of the sheet of material into panels and scrap cuttings, the sheet is transported to a cutting separator, such as is described, for example, in DE 41 24 098 C1. To prevent the cuttings from becoming separated from the panel during transport to the cutting separator, the punching dies are arranged in the punching template in such a way that, following the punching process, the cuttings remain attached to the panels via small connecting bridges. Thanks to these connecting bridges it is possible to pull the sheet with scrap cuttings and panel out of the punching machine and onto a platen in the cutting separator. Inside the cutting separator, special break-away elements envisioned on a break-away tool are pressed down onto the cutting areas, causing the scrap cuttings to detach at the connecting bridges, dropping through holes in the platen into an open space below.
Each time the cutting separator is adjusted for use with a new blank template, a new break-away tool with correspondingly positioned break-away elements and a new platen that has holes envisioned opposite to the break-away elements are needed. Therefore, implementing the adjustments for a new blank pattern is very complex.
Furthermore, it is difficult to size the connecting bridges. If they are too small, they cannot ensure that the scrap cuttings and the panel are held together, and hence they cannot ensure a secure transport. If they are too large, the connection between the scrap cuttings and the panel is too strong, resulting in quality control problems when the scrap cuttings are separated, i.e. clearly visible remnants of the connecting bridges and fissures that can result due to the large amount of force necessary to break the two apart. Because of the considerable complexity that is involved when the punching tools and the cutting separator are adjusted for a new blank template, the known method and the known apparatus for separating panels from scrap cuttings is only economical for very large production series.
From WO 99/29496 a method is known in the art that provides for the panels to be cut from a sheet of material by way of contact-free cutting, e.g. by way of laser cutting, water torches, dry ice or dry air; and the cutting process is implemented using a freely programmable machining device that is controlled by a computer.
The subject-matter of the present invention provides a method and a reliable apparatus, using simple means in terms of their construction, for separating scrap cuttings from a panel that was punched out or cut from a sheet of material and that are easily adjustable to accommodate a new blank template.
The method according to the invention is quickly and easily adjustable to accommodate a new blank template. For example, all that is required is that the second attraction surface of the cutting separator is adjusted in order to coordinate it with the geometry of the panels and scrap cuttings in the sheet of material.
If a vacuum device with a suction opening is envisioned in the cutting separator as the attraction device, the adjustment is easily achieved by covering up the areas allocated to the panel with a masking device whose air permeability level is lower than the air permeability of the suction opening.
Only minimal suction forces are necessary if the suction opening in the transport device is equipped in the area of the scrap cuttings with a partially air-permeable masking, and if the suction opening in the cutting separator is equipped in the area of the panel with a masking that is air-tight.
To separate the scrap cuttings from the panel, the transport device is moved in the direction toward the cutting separator until the sheet of material rests on top the attraction surface of the cutting separator. Afterwards the transport device is moved toward the panel-stacking device. Because the cutting separator exerts a greater attractive force on the scrap cuttings than the transport device, the cuttings remain on the cutting separator. The panels, however, continue to adhere to the attraction surface of the transport device, since the attractive force exerted by the attraction surface of the transport device is greater than the force exerted by the attraction surface of the cutting separator. The attractive force exerted by the attraction surface of the transport device is switched off in the panel-stacking device, causing the panels to fall away from this attraction surface and become deposited in the panel-stacking device.
In a preferred arrangement, a computer-controlled machining device separates the sheets of material in one cutting template in a contact-free way into panels and scrap cuttings. The same template can be used for produce the masking, resulting in a considerably reduction of the expenditure and effort that is required for adjusting a new blank template. Advantageously, the masking includes a bonding sheet with a coating on one side which the machining tool pastes onto the suction opening of the cutting separator after the cutting process.
To automate the production of panels from a sheet of material, it is advantageous to envision a panel-stacking device that can be gradually lowered in relation to the respective corresponding panel thickness, thereby allowing that the panels are always stacked on top of each other at the same height in relation to the transport device. It is also useful to provide the cutting separator with a swing device allowing it to move to a swing position in which the scrap cuttings are allowed to drop off from the attraction surface by virtue of gravity, when the attraction device on the cutting separator is switched off.